If companies, especially non-US ones, had any sanity, they'd "toast" both of them after the NSA revelations.
And even if they do - where to go? A lot of non it companies don't have even real ops ... hosting your own email and servers is expensive in that case. And potentially dangerous a modest string of bad luck could wipe you.
And precisely because a company like Microsoft or Google would do this, you need to fear them, because they would do this with other governments, too, including the Romanian one. It's not just NSA you have to fear. If the laws allow it, the Romanian government could get all your secret documents from Skydrive or Gmail, just as easily.
Did you read about the Cryptocat security bug? We learned about it because it was open source. Maybe NSA found out about it even earlier, but at least we did, too, and fixed it. Now imagine the same type of bug was in Skype. Then NSA would be the only ones who know about it.
If you are able to decipher such backdoor in the code, or do you expect the code to have a comment saying /* backdoor */ ?